How to Inset irregular (unevenly scaled) shapes?
I don't know how it evaded me the past multiple searches, but I've discovered the solution! Blender 2.8 comes with the Inset Straight Skeleton add-on bundled. Add it under Preferences>Add-Ons>Mesh>Inset Straight Skeleton. It's accessed by searching (F3) and has only two parameters: Amount and Height. Using this I was able to accomplish exactly what I wanted! Hope this helps others in the future!